Optical system for alternatively projecting adjacent images of adjacent objects or double images of a single object

ABSTRACT

An optical system is disclosed for substantially doubling the capacity of a photocopying apparatus or the like. It provides alternative modes of operation; adjacent imaging of adjacent objects or double imaging of a single object. In the adjacent imaging mode, a single projection lens projects adjacent images of two adjacent objects in a straightforward way. In the alternative double imaging mode, a pair of projection lenses projects twin images of a single object along &#34;parallel&#34; optical paths. In the double imaging mode, a field stop is included to block light from the vacated half of the object station.

BACKGROUND OF THE INVENTION

This invention relates to photocopying optical systems, and moreparticularly to an optical system for substantially doubling thecapacity of a photocopying apparatus. This invention is an improvementof the invention disclosed in application Ser. No. 756,582 filed Jan. 3,1977 by James D. Rees and Kent W. Hemphill.

By way of background, it is generally desirable to maximize the capacityor machine throughput of a photocopying apparatus for any given processspeed. Heretofore, this has been accomplished in copiers and duplicatorsby processing in the "landscape" rather than "portrait" mode. In ascanning environment, this refers to scanning of the original objectfrom one long edge to the other, the scan travel being therefore alongthe short dimension. Correspondingly, the image is laid down on thephotoreceptor and developed from one long edge to the other along theshorter edge dimension. It will be apparent that, for a given speed ofphotoreceptor, such an image is generated and developed faster than onewhich is scanned and laid down on the photoreceptor in the portraitmode, i.e. scanning in the longer direction from short edge to shortedge.

From the foregoing step from portrait to landscape operation, a naturalnext step was to enlarge the size of the object station so as toaccommodate an original object of, for example, 11 inches × 17 inches.This of course is equivalent to two adjacent 81/2 inch × 11 inch sheets.Scanning and otherwise processing of an 11 inch × 17 inch original inthe landscape mode then, becomes the equivalent of simultaneousprocessing of two adjacent 81/2 inch × 11 inch originals in the portraitmode.

The several stages just described are illustrated in FIGS. 1a, 1b, and1c. The progression may seem quite straightforward, simply providingmore photoreceptor area and arranging the object in an optimum way tomaximize its use. However, FIG. 1c also illustrates an inherent problem.That is, if the original object to be copied is not a "book" of severaldocuments but a single original, then there is not only a zero gain incapacity or throughput in the apparatus but also an attendant waste of50% of the copy paper, since a blank sheet will result from each scan ofthe blank of the object area.

It is an object of this invention to provide an improved photocopyingoptical system which is capable of alternative modes of operation: tocreate adjacent images of adjacent objects or double images from asingle object.

SUMMARY OF THE INVENTION

Briefly, the present invention is of an optical system for substantiallydoubling the capacity of a photocopying apparatus or the like. Itprovides alternative modes of operation; adjacent imaging of adjacentobjects or double imaging of a single object. In the adjacent imagingmode, a single projection lens projects adjacent images of two adjacentobjects in a straightforward way. In the alternative double imagingmode, a pair of projection lenses projects twin images of a singleobject along "parallel" optical paths. In the double imaging mode, afield stop is included to block light from the vacated half of theobject station.

DRAWING

FIG. 1 represents an original object in (1a) portrait, (1b) landscape,and (1c) adjacent portrait orientations for scanning and processing in aphotocopying apparatus.

FIG. 2 is a schematic diagram of an optical system of the prior art usedin connection with an object such as shown in FIG. 1c.

FIG. 3 is a schematic diagram of an optical system according to thepresent invention and shown in one of its alternative modes ofoperation.

FIG. 4 is a schematic diagram of the same optical system of thisinvention shown in its other alternative mode of operation.

DESCRIPTION

FIG. 1 represents at 1a an object or document O in a portrait position,at 1b a document O in a landscape position, and at 1c a pair of adjacentobject documents O and O', individually in portrait positions but thepair in a landscape position. The arrows in FIG. 1 represent thedirections in which object O might be scanned in a scanning photocopyingsystem.

FIG. 2 represents a photocopying optical system, generally indicated at2 and including a projection lens 4 disposed on an optical axis 6between conjugate object and image stations 8 and 10 respectively. Apair of documents O, O', as represented in FIG. 1c, is supported at theobject station 8 for imaging at image station 10.

To aid in the description and understanding of this invention, objectstation 8 and image station 10 can be considered as planar, and mayhereinafter be referred to as object plane 8 and image plane 10.However, it should be pointed out that the object station 8 might takethe form of a curved platen in a strip scanning photocopying system.Furthermore, image station 10 might conincide with the surface of arotating drum in a strip scanning system. In such nonplanararrangements, objects O, O' would be oriented with the scanning arrowpointing into the drawing. Correspondingly, the image station or drumsurface would be oriented on an axis extending across the drawing withthe drum rotating toward or away from the reader as indicated by thecurved arrow in FIG. 2.

Referring back to the planar conception of FIG. 2, it will be clear thatthe adjacent objects O, O' are imaged respectively as adjacent images I,I' at the image plane 10. As explained earlier, if a single object O isto be copied, it would be imaged at I and reproduced at that part of theimage station 10 as many times as desired. However, in thiscircumstance, the O' -- I' component of the optical system is wastedand, for as many copies as are to be made of object O, a correspondingnumber of wasted blank copy sheets passes through the I' portion of theimage station 10.

The foregoing is all by way of background to the present invention whichwill now be described.

Referring to FIG. 3, an optical system according to the presentinvention is indicated generally at 20. Optical system 20 includes afirst projection lens 24 on a first optical axis 26 extending betweenconjugate object and image stations 28 and 30 respectively. A secondprojection lens 22 is disposed on a second optical axis 36, alsoextending between conjugate object and image planes 28 and 30. A shutter32 is disposed adjacent to projection lens 22. In the FIG. 3 arrangementof this optical system, shutter 32 is represented as closed so thatprojection lens 22 is inoperative to project an image from object plane28 to image plane 30.

In the arrangement of FIG. 3, the single projection lens 24 operates inthe same manner as lens 4 in the earlier described optical system ofFIG. 2 to project adjacent images of adjacent objects. Assuming thepresence of a pair of object documents O and O', such as in FIG. 1c, theresulting projection is of adjacent images I and I' at the image plane30 which might ultimately appear in "saddle" relationship on a singlelarge support sheet. This "saddle" mode of operation of optical system20 alludes to that term which in graphic arts generally refers to thearrangement of two pages of content folded in the middle. Images I andI' might also be placed on separate sheets of paper passing in parallelthrough the system. The final copy arrangement, whether "saddle" orseparate, is immaterial to this invention.

The object side of the optical system 20, between object plane 28 andprojection lenses 22 and 24 is disposed in an integrating illuminationcavity 34 defined by walls 38 having a diffuse reflective inner surface39 to enhance illumination efficiency. Light sources 40 are disposedwithin extensions of the cavity 34 so that object illumination may be atailored combination of direct and diffusely reflected light.

The enclosure defining the integrating illumination cavity 34 may bemoveable between alternative positions so that the cavity exposes theentire object field, as shown in FIG. 3 in the saddle mode of operation,or so that the cavity exposes only half of the object field, as in FIG.4 in the double imaging mode of operation. The phantom line in FIG. 4represents the alternative position of the right cavity wall as 38a.

Referring now to FIG. 4, the same optical system 20 is shown in itsalternative mode of operation for double imaging from a single object.In this configuration, shutter 32 is represented as open with respect toprojection lens 22. An additional element shown in FIG. 4 is a fieldstop or mask 42 in the path of light propagating from that part of theobject station now vacated by object O'. The purpose of stop 42 is toblank out, and black out the vacated portion of the platen 28, thus toprevent light from that portion of the object station reaching the imagestation and washing out the image. In this configuration, twin images ofthe single object O are projected along "parallel" optical paths by thetwo projection lenses 22 and 24.

Field stop 42 is shown as blocking the cone of light propagating fromthe vacant half of the platen 28. Stop 42 might be disposed at anyposition in the path of the propagating light cone, but it is preferredin this invention to locate it on the image side of lens 24. Incopending application Ser. No. 756,582 a mask 34 is disposed immediatelyunder the platen 28. This extended black area absorbs an appreciableamount of light at the expense of illumination efficiency. To eliminatethis "light sink", stop 42 of this invention is located on the dark sideof the lens. Field stop 42 is moved out of the optical system in theFIG. 3 saddle mode of operation.

The details of shutter 32 and field stop 42 are not material to thisinvention. The opening and closing of shutter 32 relative to theprojecting lens 22 is represented simply by the arrow whichschematically represents reciprocation of the shutter into and out ofthe path of light to the lens 22. Similarly, field stop 42 isschematically represented by an arrow as moveable into and out ofmasking relationship to the vacated half of platen 28.

It will be appreciated from the foregoing description that an improvedoptical system has been provided for substantially doubling the capacityor throughput of a photocopying apparatus by the alternative modes ofoperation disclosed.

The foregoing description of an embodiment of this invention is given byway of illustration and not of limitation. The concept and scope of theinvention are limited only by the following claims and equivalentsthereof which may occur to others skilled in the art.

What is claimed is:
 1. An optical system for alternatively projecting animage of a full object field in a first mode of operation and projectinga plurality of images of a partial object field in a second mode ofoperation, including:an object station defining an object field, saidobject field disposed within an integrating illumination cavity definedby an enclosure having a diffuse reflective inner member, an imagestation defining an image field, a first projection lens disposed on afirst optical axis between said object and image stations, said objectand image fields being respectively in object and image conjugaterelationship to said first projection lens, a second projection lensdisposed on a second optical axis between said object and imagestations, a first part of said object field and a first part of saidimage field being respectively in object and image conjugaterelationship to said first projection lens, said first part of saidobject field and a second part of said image field being respectively inobject and image conjugate relationship to said second projection lens,a shutter operatively disposed relative to said second projection lensto close optical communication through said second projection lens insaid first mode of operation and to open optical communication throughsaid second projection lens in said second mode of operation, and afield stop operatively disposed in said image field and movable betweena clear position to permit unobstructed optical communication betweensaid object station and said image station in said first mode ofoperation and a masking position to mask out a second part of saidobject field in said second mode of operation.
 2. An optical system asdefined in claim 1 wherein said enclosure is movable between a firstdisposition in said first mode of operation in which the entire objectfield is exposed to said illumination cavity and a second disposition insaid second mode of operation in which said first half of said objectfield is exposed to said illumination cavity.